It is now well known that the central function of the bioenergetic machinery of respiratory and photosynthetic membranes is to convert the free energy between oxidants and reductants into a transmembrane electrical potential and a proton gradient, and that this drives essential energy requiring processes of ion and metaholite transport and ATP production. A challenge is to understand how electron transfers are controlled in these membrane proteins that are crowded with highly reactive intermediates. The aim of the proposed experimental work is to determine the fundamental principles of molecular design and engineering that are responsible for the governance of the rates and directional specificity of electron transfers through protein directed across bioenergetic membranes. The Langmuir-Blodgett film balance and self-assembled monolayers will be used to manipulate the proteins into a vectorial configuration that facilitates structure determination and ready investigation of charge separating events. These assemblies will be used to monitor, modulate and activate charge separating events in respiratory and photosynthetic redox proteins. A second approach will develop novel synthetic constructions of protein and cofactors, designed and engineered to provide minimal water soluble structures that perform critical functions of the native protein. It is hoped in the long term that these synthetic redox proteins will access problems difficult, if not impossible, with the membrane proteins, including offering a simpler path towards crystallization and structural resolution of the active parts of their natural counterparts. In describing the engineering parameters of electron transfer driven charge separation, the regions of normal efficient operation will be identified. Recognition of the functional tolerances, therefore, define the threshold of dysfunction that underlies pathological conditions.